I've set my Desktop File->Workbook Locale to be local (English Australia) and date formats are interpreted correctly (DD/MM/YYYY).

When twb and extract are published to Tableau Online they are initially correct.

Yet when the daily extract refreshes the dates for a field are incorrectly reinterpreted as US date format (MM/DD/YYYY). So it seems to be related to changing back to US defaults, with our Tableau Online being hosted on 'us-east-1.online.tableau.com'.

How can I get Tableau Online to have the date format set as default to be set to a specific local/region?

I need to work in the same date format in Desktop and Online. The display of the date is not an issue, instead it is Tableau's interpretation of the dates. So in Desktop it correctly interprets 12/07/2017 as July 12th 2017, yet when published to Online it is interpreted as December 7th 2017.

Unfortunately the display is not the issue, which I am not really concerned about, rather Tableau's interpretation of the date field.

So in Desktop it correctly interprets 12/07/2017 as July 12th 2017, yet when published to Online it is interpreted as December 7th 2017. While I could change the format in Desktop to interpret days and months backwards assuming that it would then be interpreted correctly Online this would mean that the visualisation in Desktop won't make sense until it gets published. Neither do I want to change my Workbook Locale settings to be US region.

Another funny thing is that the first time it is published the date format is correctly interpreted (Australia format) with no Decemeber 2017 dates. But once the extract refreshes the it reverts to interprets the dates differently and starts displaying Dec' 2017 dates.

The extract is based on two sources, a Google Spreadsheet joined to a RDS database. The Google Sheet is the date field (formatted like '17/12/2016 12:30:00') that's changing between Desktop and Online.